Adding AES-256 and AES-256-CTR encryption modes

src/controller/base-stream-controller.ts

@@ -7,6 +7,10 @@ import { ErrorDetails, ErrorTypes } from '../errors';
 import { ChunkMetadata } from '../types/transmuxer';
 import { appendUint8Array } from '../utils/mp4-tools';
 import { alignStream } from '../utils/discontinuities';
+import {
+  isFullSegmentEncryption,
+  getAesModeFromFullSegmentMethod,
+} from '../utils/encryption-methods-util';
 import {
   findFragmentByPDT,
   findFragmentByPTS,
@@ -481,7 +485,7 @@ export default class BaseStreamController
           payload.byteLength > 0 &&
           decryptData?.key &&
           decryptData.iv &&
-          decryptData.method === 'AES-128'
+          isFullSegmentEncryption(decryptData.method)
         ) {
           const startTime = self.performance.now();
           // decrypt init segment data
@@ -490,6 +494,7 @@ export default class BaseStreamController
               new Uint8Array(payload),
               decryptData.key.buffer,
               decryptData.iv.buffer,
+              getAesModeFromFullSegmentMethod(decryptData.method),
             )
             .catch((err) => {
               hls.trigger(Events.ERROR, {

src/controller/subtitle-stream-controller.ts

@@ -9,6 +9,10 @@ import { PlaylistLevelType } from '../types/loader';
 import { Level } from '../types/level';
 import { subtitleOptionsIdentical } from '../utils/media-option-attributes';
 import { ErrorDetails, ErrorTypes } from '../errors';
+import {
+  isFullSegmentEncryption,
+  getAesModeFromFullSegmentMethod,
+} from '../utils/encryption-methods-util';
 import type { NetworkComponentAPI } from '../types/component-api';
 import type Hls from '../hls';
 import type { FragmentTracker } from './fragment-tracker';
@@ -360,7 +364,7 @@ export class SubtitleStreamController
       payload.byteLength > 0 &&
       decryptData?.key &&
       decryptData.iv &&
-      decryptData.method === 'AES-128'
+      isFullSegmentEncryption(decryptData.method)
     ) {
       const startTime = performance.now();
       // decrypt the subtitles
@@ -369,6 +373,7 @@ export class SubtitleStreamController
           new Uint8Array(payload),
           decryptData.key.buffer,
           decryptData.iv.buffer,
+          getAesModeFromFullSegmentMethod(decryptData.method),
         )
         .catch((err) => {
           hls.trigger(Events.ERROR, {

src/crypt/aes-crypto.ts

@@ -1,13 +1,32 @@
+import { DecrypterAesMode } from './decrypter-aes-mode';
+
 export default class AESCrypto {
   private subtle: SubtleCrypto;
   private aesIV: Uint8Array;
+  private aesMode: DecrypterAesMode;
 
-  constructor(subtle: SubtleCrypto, iv: Uint8Array) {
+  constructor(subtle: SubtleCrypto, iv: Uint8Array, aesMode: DecrypterAesMode) {
     this.subtle = subtle;
     this.aesIV = iv;
+    this.aesMode = aesMode;
   }
 
   decrypt(data: ArrayBuffer, key: CryptoKey) {
-    return this.subtle.decrypt({ name: 'AES-CBC', iv: this.aesIV }, key, data);
+    switch (this.aesMode) {
+      case DecrypterAesMode.cbc:
+        return this.subtle.decrypt(
+          { name: 'AES-CBC', iv: this.aesIV },
+          key,
+          data,
+        );
+      case DecrypterAesMode.ctr:
+        return this.subtle.decrypt(
+          { name: 'AES-CTR', counter: this.aesIV, length: 64 }, //64 : NIST SP800-38A standard suggests that the counter should occupy half of the counter block
+          key,
+          data,
+        );
+      default:
+        throw new Error(`[AESCrypto] invalid aes mode ${this.aesMode}`);
+    }
   }
 }

src/crypt/decrypter-aes-mode.ts

@@ -0,0 +1,4 @@
+export const enum DecrypterAesMode {
+  cbc = 0,
+  ctr = 1,
+}

src/crypt/decrypter.ts

@@ -4,6 +4,7 @@ import AESDecryptor, { removePadding } from './aes-decryptor';
 import { logger } from '../utils/logger';
 import { appendUint8Array } from '../utils/mp4-tools';
 import { sliceUint8 } from '../utils/typed-array';
+import { DecrypterAesMode } from './decrypter-aes-mode';
 import type { HlsConfig } from '../config';
 
 const CHUNK_SIZE = 16; // 16 bytes, 128 bits
@@ -81,10 +82,11 @@ export default class Decrypter {
     data: Uint8Array | ArrayBuffer,
     key: ArrayBuffer,
     iv: ArrayBuffer,
+    aesMode: DecrypterAesMode,
   ): Promise<ArrayBuffer> {
     if (this.useSoftware) {
       return new Promise((resolve, reject) => {
-        this.softwareDecrypt(new Uint8Array(data), key, iv);
+        this.softwareDecrypt(new Uint8Array(data), key, iv, aesMode);
         const decryptResult = this.flush();
         if (decryptResult) {
           resolve(decryptResult.buffer);
@@ -93,7 +95,7 @@ export default class Decrypter {
         }
       });
     }
-    return this.webCryptoDecrypt(new Uint8Array(data), key, iv);
+    return this.webCryptoDecrypt(new Uint8Array(data), key, iv, aesMode);
   }
 
   // Software decryption is progressive. Progressive decryption may not return a result on each call. Any cached
@@ -102,8 +104,13 @@ export default class Decrypter {
     data: Uint8Array,
     key: ArrayBuffer,
     iv: ArrayBuffer,
+    aesMode: DecrypterAesMode,
   ): ArrayBuffer | null {
     const { currentIV, currentResult, remainderData } = this;
+    if (aesMode !== DecrypterAesMode.cbc || key.byteLength !== 16) {
+      logger.warn('SoftwareDecrypt: can only handle AES-128-CBC');
+      return null;
+    }
     this.logOnce('JS AES decrypt');
     // The output is staggered during progressive parsing - the current result is cached, and emitted on the next call
     // This is done in order to strip PKCS7 padding, which is found at the end of each segment. We only know we've reached
@@ -146,38 +153,39 @@ export default class Decrypter {
     data: Uint8Array,
     key: ArrayBuffer,
     iv: ArrayBuffer,
+    aesMode: DecrypterAesMode,
   ): Promise<ArrayBuffer> {
     const subtle = this.subtle;
     if (this.key !== key || !this.fastAesKey) {
       this.key = key;
-      this.fastAesKey = new FastAESKey(subtle, key);
+      this.fastAesKey = new FastAESKey(subtle, key, aesMode);
     }
     return this.fastAesKey
       .expandKey()
-      .then((aesKey) => {
+      .then((aesKey: CryptoKey) => {
         // decrypt using web crypto
         if (!subtle) {
           return Promise.reject(new Error('web crypto not initialized'));
         }
         this.logOnce('WebCrypto AES decrypt');
-        const crypto = new AESCrypto(subtle, new Uint8Array(iv));
+        const crypto = new AESCrypto(subtle, new Uint8Array(iv), aesMode);
         return crypto.decrypt(data.buffer, aesKey);
       })
       .catch((err) => {
         logger.warn(
           `[decrypter]: WebCrypto Error, disable WebCrypto API, ${err.name}: ${err.message}`,
         );
 
-        return this.onWebCryptoError(data, key, iv);
+        return this.onWebCryptoError(data, key, iv, aesMode);
       });
   }
 
-  private onWebCryptoError(data, key, iv): ArrayBuffer | never {
+  private onWebCryptoError(data, key, iv, aesMode): ArrayBuffer | never {
     const enableSoftwareAES = this.enableSoftwareAES;
     if (enableSoftwareAES) {
       this.useSoftware = true;
       this.logEnabled = true;
-      this.softwareDecrypt(data, key, iv);
+      this.softwareDecrypt(data, key, iv, aesMode);
       const decryptResult = this.flush();
       if (decryptResult) {
         return decryptResult.buffer;

src/crypt/fast-aes-key.ts

@@ -1,16 +1,35 @@
+import { DecrypterAesMode } from './decrypter-aes-mode';
+
 export default class FastAESKey {
   private subtle: any;
   private key: ArrayBuffer;
+  private aesMode: DecrypterAesMode;
 
-  constructor(subtle, key) {
+  constructor(subtle, key, aesMode: DecrypterAesMode) {
     this.subtle = subtle;
     this.key = key;
+    this.aesMode = aesMode;
   }
 
   expandKey() {
-    return this.subtle.importKey('raw', this.key, { name: 'AES-CBC' }, false, [
-      'encrypt',
-      'decrypt',
-    ]);
+    const subtleAlgoName = getSubtleAlgoName(this.aesMode);
+    return this.subtle.importKey(
+      'raw',
+      this.key,
+      { name: subtleAlgoName },
+      false,
+      ['encrypt', 'decrypt'],
+    );
+  }
+}
+
+function getSubtleAlgoName(aesMode: DecrypterAesMode) {
+  switch (aesMode) {
+    case DecrypterAesMode.cbc:
+      return 'AES-CBC';
+    case DecrypterAesMode.ctr:
+      return 'AES-CTR';
+    default:
+      throw new Error(`[FastAESKey] invalid aes mode ${aesMode}`);
   }
 }

src/demux/sample-aes.ts

@@ -4,6 +4,7 @@
 
 import { HlsConfig } from '../config';
 import Decrypter from '../crypt/decrypter';
+import { DecrypterAesMode } from '../crypt/decrypter-aes-mode';
 import { HlsEventEmitter } from '../events';
 import type {
   AudioSample,
@@ -30,6 +31,7 @@ class SampleAesDecrypter {
       encryptedData,
       this.keyData.key.buffer,
       this.keyData.iv.buffer,
+      DecrypterAesMode.cbc,
     );
   }
 

src/demux/transmuxer.ts

@@ -10,6 +10,10 @@ import { AC3Demuxer } from './audio/ac3-demuxer';
 import MP4Remuxer from '../remux/mp4-remuxer';
 import PassThroughRemuxer from '../remux/passthrough-remuxer';
 import { logger } from '../utils/logger';
+import {
+  isFullSegmentEncryption,
+  getAesModeFromFullSegmentMethod,
+} from '../utils/encryption-methods-util';
 import type { Demuxer, DemuxerResult, KeyData } from '../types/demuxer';
 import type { Remuxer } from '../types/remuxer';
 import type { TransmuxerResult, ChunkMetadata } from '../types/transmuxer';
@@ -115,8 +119,10 @@ export default class Transmuxer {
     } = transmuxConfig;
 
     const keyData = getEncryptionType(uintData, decryptdata);
-    if (keyData && keyData.method === 'AES-128') {
+    if (keyData && isFullSegmentEncryption(keyData.method)) {
       const decrypter = this.getDecrypter();
+      const aesMode = getAesModeFromFullSegmentMethod(keyData.method);
+
       // Software decryption is synchronous; webCrypto is not
       if (decrypter.isSync()) {
         // Software decryption is progressive. Progressive decryption may not return a result on each call. Any cached
@@ -125,6 +131,7 @@ export default class Transmuxer {
           uintData,
           keyData.key.buffer,
           keyData.iv.buffer,
+          aesMode,
         );
         // For Low-Latency HLS Parts, decrypt in place, since part parsing is expected on push progress
         const loadingParts = chunkMeta.part > -1;
@@ -138,7 +145,12 @@ export default class Transmuxer {
         uintData = new Uint8Array(decryptedData);
       } else {
         this.decryptionPromise = decrypter
-          .webCryptoDecrypt(uintData, keyData.key.buffer, keyData.iv.buffer)
+          .webCryptoDecrypt(
+            uintData,
+            keyData.key.buffer,
+            keyData.iv.buffer,
+            aesMode,
+          )
           .then((decryptedData): TransmuxerResult => {
             // Calling push here is important; if flush() is called while this is still resolving, this ensures that
             // the decrypted data has been transmuxed

src/loader/fragment-loader.ts

@@ -336,8 +336,11 @@ function createLoaderContext(
   if (Number.isFinite(start) && Number.isFinite(end)) {
     let byteRangeStart = start;
     let byteRangeEnd = end;
-    if (frag.sn === 'initSegment' && frag.decryptdata?.method === 'AES-128') {
-      // MAP segment encrypted with method 'AES-128', when served with HTTP Range,
+    if (
+      frag.sn === 'initSegment' &&
+      isMethodFullSegmentAesCbc(frag.decryptdata?.method)
+    ) {
+      // MAP segment encrypted with method 'AES-128' or 'AES-256' (cbc), when served with HTTP Range,
       // has the unencrypted size specified in the range.
       // Ref: https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-08#section-6.3.6
       const fragmentLen = end - start;
@@ -372,6 +375,10 @@ function createGapLoadError(frag: Fragment, part?: Part): LoadError {
   return new LoadError(errorData);
 }
 
+function isMethodFullSegmentAesCbc(method) {
+  return method === 'AES-128' || method === 'AES-256';
+}
+
 export class LoadError extends Error {
   public readonly data: FragLoadFailResult;
   constructor(data: FragLoadFailResult) {

src/loader/key-loader.ts

@@ -194,6 +194,8 @@ export default class KeyLoader implements ComponentAPI {
         }
         return this.loadKeyEME(keyInfo, frag);
       case 'AES-128':
+      case 'AES-256':
+      case 'AES-256-CTR':
         return this.loadKeyHTTP(keyInfo, frag);
       default:
         return Promise.reject(

src/loader/level-key.ts

@@ -2,6 +2,7 @@ import {
   changeEndianness,
   convertDataUriToArrayBytes,
 } from '../utils/keysystem-util';
+import { isFullSegmentEncryption } from '../utils/encryption-methods-util';
 import { KeySystemFormats } from '../utils/mediakeys-helper';
 import { mp4pssh } from '../utils/mp4-tools';
 import { logger } from '../utils/logger';
@@ -51,13 +52,14 @@ export class LevelKey implements DecryptData {
     this.keyFormatVersions = formatversions;
     this.iv = iv;
     this.encrypted = method ? method !== 'NONE' : false;
-    this.isCommonEncryption = this.encrypted && method !== 'AES-128';
+    this.isCommonEncryption =
+      this.encrypted && !isFullSegmentEncryption(method);
   }
 
   public isSupported(): boolean {
     // If it's Segment encryption or No encryption, just select that key system
     if (this.method) {
-      if (this.method === 'AES-128' || this.method === 'NONE') {
+      if (isFullSegmentEncryption(this.method) || this.method === 'NONE') {
         return true;
       }
       if (this.keyFormat === 'identity') {
@@ -88,16 +90,15 @@ export class LevelKey implements DecryptData {
       return null;
     }
 
-    if (this.method === 'AES-128' && this.uri && !this.iv) {
+    if (isFullSegmentEncryption(this.method) && this.uri && !this.iv) {
       if (typeof sn !== 'number') {
         // We are fetching decryption data for a initialization segment
-        // If the segment was encrypted with AES-128
+        // If the segment was encrypted with AES-128/256
         // It must have an IV defined. We cannot substitute the Segment Number in.
-        if (this.method === 'AES-128' && !this.iv) {
-          logger.warn(
-            `missing IV for initialization segment with method="${this.method}" - compliance issue`,
-          );
-        }
+        logger.warn(
+          `missing IV for initialization segment with method="${this.method}" - compliance issue`,
+        );
+
         // Explicitly set sn to resulting value from implicit conversions 'initSegment' values for IV generation.
         sn = 0;
       }

src/utils/encryption-methods-util.ts

@@ -0,0 +1,21 @@
+import { DecrypterAesMode } from '../crypt/decrypter-aes-mode';
+
+export function isFullSegmentEncryption(method: string): boolean {
+  return (
+    method === 'AES-128' || method === 'AES-256' || method === 'AES-256-CTR'
+  );
+}
+
+export function getAesModeFromFullSegmentMethod(
+  method: string,
+): DecrypterAesMode {
+  switch (method) {
+    case 'AES-128':
+    case 'AES-256':
+      return DecrypterAesMode.cbc;
+    case 'AES-256-CTR':
+      return DecrypterAesMode.ctr;
+    default:
+      throw new Error(`invalid full segment method ${method}`);
+  }
+}

tests/index.js

@@ -26,6 +26,7 @@ import './unit/controller/subtitle-track-controller';
 import './unit/controller/timeline-controller-nonnative';
 import './unit/controller/timeline-controller';
 import './unit/crypt/aes-decryptor';
+import './unit/crypt/decrypter';
 import './unit/demuxer/adts';
 import './unit/demuxer/base-audio-demuxer';
 import './unit/demuxer/id3';